Cored welding electrodes are widely used in arc welding processes to join metals through deposition of molten metal to a workpiece using an arc between the electrode and the workpiece. The welding electrode is directed by a wire feeder toward the welding operation in the form of a continuous wire fed through a welding torch cable from a wire supply, and an arc is generated at the torch between the end of the electrode and the workpiece for melting and depositing electrode material to a weld in a controlled fashion. Many arc welding processes, such as metal inert gas (MIG) techniques, employ an external inert shielding gas such as argon around the welding arc to inhibit oxidation or nitridation of the molten metal. Non-inert external shielding gases such as CO2 may also be used, whereby such processes are sometimes generally referred to as gas metal arc welding (GMAW). Other arc shielding processes similarly provide a protective shield of vapor to cover the arc and slag to protect the molten weld pool as it cools. The molten electrode material may be transferred to the workpiece by several mechanisms or processes, such as short-circuit welding, spray arc welding, and pulse welding.
Cored welding electrodes include a tubular core or interior region surrounded by an outer sheath, where the core may include fluxing elements (e.g., flux cored electrodes), deoxidizing and denitriding agents, alloying materials, and elements that increase toughness and strength, improve corrosion resistance, and stabilize a welding arc. Flux cored arc welding (FCAW) processes employ flux-cored electrodes which include flux within the electrode core to produce an extensive slag cover during welding, where the slag protects and shapes the resulting weld bead as it cools. These processes also use a gas shield to protect the weld zone from detrimental atmospheric contamination (e.g., particularly from oxygen and/or nitrogen), where the shielding gas can be applied externally, or it may be generated from the decomposition of gas forming ingredients contained in the electrode core itself (sometimes referred to as a self-shielding flux cored electrode). In such self-shielded FCAW, the heat of the arc causes decomposition and some vaporization of the electrode's flux core, which partially protects the molten metal. For both self-shielding and gas shielded FCAW processes, it is desirable to weld with a stable electrical arc between the cored electrode and the workpiece, wherein arc stabilizing effects are primarily controlled through additives in the core fill material of the flux-cored welding electrode. In this regard, granular aluminum is sometimes provided along with other fill materials in flux-cored electrodes to improve welding arc stability and to reduce fumes during the welding process. However, conventional metal core electrodes used in gas shielded processes typically do not include arc stabilizing components in the core.
Various types of flux-cored welding electrodes are designed and manufactured for self-shielding and externally shielded FCAW applications. Such cored welding electrodes are typically constructed beginning with a flat metal strip that is initially formed first into a “U” or “V” shape, for example, as shown in Bernard U.S. Pat. No. 2,785,285, Sjoman U.S. Pat. No. 2,944,142, and Woods U.S. Pat. No. 3,534,390, with flux, alloying elements, and/or other core fill materials being deposited into the “U”, after which the strip is closed into a tubular configuration by a series of forming rolls. The resulting closed cored electrode structure is then drawn to a final wire diameter and the outer sheath surface is treated with a feeding lubricant to enhance feedability during welding. In a typical welding system, the welding electrode is fed through a welder cable, sometimes referred to as a torch cable, which can be five to twenty feet or more in length, to a welding gun or torch, and then to the welding process at which the welding arc is established. The feeding lubricant applied on the finished diameter of the electrode helps the electrode in traveling through the welding torch cable. It is therefore a continuing goal to provide cored welding electrode wire having consistent arc stabilizer content and suitable feedability for use with automatic wire feeders in self-shielded and gas shielded FCAW processes.